/*
To the Max
Time Limit: 1 Second      Memory Limit: 32768 KB

Problem

Given a two-dimensional array of positive and negative integers, a sub-rectangle is any contiguous sub-array of size 1 x 1 or greater located within the whole array. The sum of a rectangle is the sum of all the elements in that rectangle. In this problem the sub-rectangle with the largest sum is referred to as the maximal sub-rectangle.

As an example, the maximal sub-rectangle of the array:

0 -2 -7 0
9 2 -6 2
-4 1 -4 1
-1 8 0 -2

is in the lower left corner:

9 2
-4 1
-1 8

and has a sum of 15.

The input consists of an N x N array of integers. The input begins with a single positive integer N on a line by itself, indicating the size of the square two-dimensional array. This is followed by N 2 integers separated by whitespace (spaces and newlines). These are the N 2 integers of the array, presented in row-major order. That is, all numbers in the first row, left to right, then all numbers in the second row, left to right, etc. N may be as large as 100. The numbers in the array will be in the range [-127,127].


Output

Output the sum of the maximal sub-rectangle.


Example

Input

4
0 -2 -7 0 9 2 -6 2
-4 1 -4 1 -1
8 0 -2

Output

15 
*/

#include <iostream>
using namespace std;

int main(){
	int max=-127,count=0,N=0, t, ret;
	int **M;
	int ***RV;
	int ***CV;

	cin>>N;
	M = new int* [N];
	RV = new int** [N];
	CV = new int** [N];
	for (int i=0;i<N;i++) {
		M[i]=new int[N];
		RV[i]=new int* [N];
		CV[i]=new int* [N];
	}

	for (int i=0;i<N;i++)
		for (int j=0;j<N;j++) {
			RV[i][j]=new int[N];
			CV[i][j]=new int[N];
		}

	while (cin>>t) {
		if (max<t) max = t;
		M[count/N][count%N] = t;
		++ count;
	}

	for (int i=0;i<N;i++) 
		for (int j=0;j<N;j++) {
			RV[i][j][j] = M[i][j];
			CV[i][j][i] = M[i][j];
		}

	for (int i=0;i<N;i++) 
		for (int j=0;j<N;j++) 
			for (int k=j+1;k<N;k++) {
				RV[i][j][k] = RV[i][j][k-1]+M[i][k];
				CV[j][i][k] = CV[j][i][k-1]+M[k][i];
			}


	for (int i=0;i<N;i++) 
		for (int j=0;j<N;j++) 
			for (int x=i+1;x<N;x++) 
				for (int y=j+1;y<N;y++) {
					if ( RV[i][j][y]<=0 || RV[x][j][y]<=0 ||
							CV[i][j][x]<=0 || CV[i][y][x]<= 0)
						continue;

					ret =0;
					if (x-i>y-j) {
						for (int n=j;n<=y;n++) 
							ret += CV[i][n][x];
					} else {
						for (int n=i;n<=x;n++) 
							ret += RV[n][j][y];
					}

					if (ret>max) max = ret;
				}

	cout<<max<<endl;
}
